Magnetic chuck



0. S. WALKER.

MAGNETIC CHUCK.

APPLICATION FILED MAR. 8. I919.

1,329,733. Patented Feb. 3,1920.

Mm 43 m UNITED STATES PATENT OFFICE.

OAKLEY S. WALKER, OF WORCESTER, MASSACHUSETTS, ASSIGN OR TO O. S. WALKER0E WORCESTER, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

MAGNETIC CHUCK.

To all whom it may concern:

Be it known that I, OAKLEY S. WALKER, a citizen of the United States,residing at Worcester, in the county of Worcester and Commonwealth ofMassachusetts, have invented a new and useful Improvement in MagneticChucks, of which the following, taken in connection with theaccompanying drawings, is a specification.

The present invention relates to magnetic "chucks, and has particularreference to a novel and improved construction and arrangement of partsfor a device of this class, whereby the same affords a finely dividedwork holding face which is peculiarly adapted for the retention of smallpieces of work. The invention resides primarily in a new principle ofconstruction and a novel inter-relation for the pole pieces of thechuck, which is fully set forth in the follow ing description andillustrated in the accompanying drawings, wherein Figure 1 is a partialtop plan view of a chuck embodying my invention.

Fig. 2 is a vertical sectional view of said chuck, taken substantiallyin a diametrical plane.

Fig. 3 is a detached view of one of the polar sections of the face plateof the chuck.

Fig. 4 is a detached view showing two of such polar sections incooperative position.

Fig.5 is a fragmentary sectional view on the line 5-5, Fig. 4, showingthe manner in which one row of pole piece projections is insulated fromthe base of the adjacent pole iece. .f p Like reference characters referto like parts in the different figures.

Referring to the drawings, the numeral '1 denotes the base or shell ofthe chuck, which is here shown as circular in form and adapted to berotated, although obviously the principles of the invention as hereindisclosed are equally applicable to a rectangular stationary chuck, orany other shape desired. The shell 1 provides a central aperture 2 forthe attachment of a shaft or spindle, not' shown, by means of which thechuck may be rotated. The hollow interior of the shell 1 is adapted toreceive and support'a plurality of separate core members 3, 3, which arehere s own as radially arranged for'the circular type of ehuckillusti-ated, although obviously for a rectangular Specification ofLetters Patent.

Patented Feb. 3, 1920.

Application filed March 8, 1919. Serial-No. 281,362.

chuck these core members would be arranged I longitudinally in a row.Each core member 3, which in horizontal section is substantiallytriangular, has an individual coil or windin 4, the coils of adjacentcore members being oppositely wound or otherwise so arranged as toimpart opposite magnetic polarity to adjacent cores. The coils 4 aresuitably connected in any well known manner to the usual contact rings 5and 6 which depend from the shell 1 and are suitably insulatedtherefrom, said rings rotating in contact with suitable brushes or thelike, not shown, whereby to secure the passage of electric currentthrough the coils 4 when the chuck is energized.

The face plate of the chuck is adapted to cover and inclose the shell 1,and is held in place by suitable screws or bolts 7, 7, which pass fromthe bottom of the shell up through the core members 3, 3, and into saidface plate, which latter is thus detachable when desired to affordaccess to the interior of the chuck for purposes of inspection orrepair. Said face plate consists of an annular rim 8 which rests on theupper edge of shell 1 and which incloses a circular space, which isadapted to be filled substantially by the several polar sections oftheface plate, one of which is shown detached in Fig. 3. These polarsections, each indicated by the numeral 9, correspond in number to thenumber of core members 3. Each polar section 9 comprises a base portion10 of substantially triangular shape, corresponding to the shape of itsassociated core member 3, and adapted to make contact with the uppersurface of said core member when the face plate is in position.

Extending laterally and upwardly from each side of the base portion 10are two series of spaced segmental projections 11 and 12, theprojections 11 on. one side of the base portion 10 being staggered withrespect to the projections 12 on the other side, so that each'projection11 or 12 is in substantial alinement with the gap or space that occursin the row of projectlons on the.

the center of the chuck, but in a rectangular chuck, having its polarsections parallel in a straight row, the projections would be of thesame length throughout.

As herein shown also, it is referable to decrease the width or radial ticknesses of the projections 11 and 12 toward the center of the chuck inorder to obtain near the center of the face plate a more finel dividedarea. This decrease in the widt of the projections 11 and 12, near thecenter of the face plate, is accompanied by a corresponding decrease inthe width of the nonmagnetic gaps between said sections, as shown inFig. 1. This feature contributes to the capability of the face plate forholding extremely small pieces of work, especially at the centralportions thereof.

When two of the polar sections 9, 9, are

placed adjacent each other, in radial position, the projections 11, 11,of one of them enter between the projections 12, 12 of the other, asshown in Fig. 4. In the construction of the face plate as shown. in Fig.1,

this method of assemblage is followed for the entire surface, and theproportion of parts is such that a nonmagnetic gap is formed completelyaround every individual projection 11 or 12, since the spaces betweenthe projections 11 and 12 of each row are greater in area than the proectlons from the adjacent pole sections which enter sald spaces. Thecompleted chuck face therefore consists, as show n in Fig. 1, of aplurality of rows of radially arranged sections or pieces, having radialnonmagnetic gaps 13, and also having concentric nonmagnetic gaps 14. Inthe assembly of the face plate these gaps 13 and 14 are filled withnonmagnetic material in the usual manner, as by inverting the face plateand pouring said nonmagnetic material so as to cause it to flow aroundeach individual projection 11 or 12, and to completely segregate eachprojection from every other adjacent projection- The several polarsections 9, 9, of the face plate are each caused to interlock with therim 8 by non magnetic material filling the gap 15, the latter being soconstructed as to form interlocking tongues v16, 16, with the rim andwith the polar sections 9. At the center, the polar sections 9 aresuitably supported and insulated from the central block or bushing 17 bymeans of non-magnetic material fillin the ga 18.

Vhen t e face plate isin position, each polar section 9 is disposed incontact with one of the core members 3. Therefore each polar section 9and its integral projection 11 and 12 is of the opposite magneticpolarity from the adjacent polar sections 9,

9, and their integral projection 11 and 12 on each side of 1t. Conseuently, the entire work supporting and olding surface of the chuck ismade up of the projections 11 and 12 of these polar sections 9, givingthereby an extremely finely divided surface.

Each projection 11 or 12 is, as shown in Fig. 4, of the oppositemagnetic polarity from every adjacent projectlon, both as regards thoseon opposite sides of it, and those at opposite ends of it. In view ofthis fact the number'of actual magnetic gaps presented by the facefplate is greatly increased, thus giving said ace plate the abilit tohold extremely small work at any an tion thereof.

It will be noted that the innermost projection of each polar section, onaccount of the extreme thinness of the base portion 10, is offset tosuch an extent as practically to overhang said base, it being clear thatthis construction permits the projections to be brought closer to thecenter than would otherwise be the case.

I claim,

1. In a magnetic chuck, a pole piece presenting a plurality ofindependent spaced flush surfaces, and an identical adj acent pole pieceof opposite polarity presenting similar surfaces interposed betweenthose of the first pole piece.

2. A' magnetic chuck, having a work holding face composed of a plurahtyof indentical pole pieces, each of the latter presenting on said face aplurality of independent every porspaced flush surfaces.

3. In a magnetic chuck, a pole piece providing a discontinuous workholdin face composed of a plurality of isolate flush surfaces arrange inrows.

4. In a magnetic chuck, a pole piece providing a discontinuous workholdin face composed of a plurality of isolated flus surfaces arrangedin staggered rows.

5. In a magnetic chuck, a work holding face comprising adjacent sectionsof opposite polarity, each section presenting on said work holdin face aplurality of independent flush sur aces disposed in alinement with aplurality of similar surfaces on adjacent sections.

6. In a magnetic chuck, a work holding face comprising adjacent sectionsof opposite polarity, each section having a row of upstanding spacedprojections disposed in alternating relation to projections on adjacentpole sections.

7. In a magnetic chuck, a work holding face composed wholly of aplurality of rows of magnetized sections, each section being of oppositepolarity from the adjacent sections in its row, and from thecorresponding sections in adjacent rows.

8. In a magnetic chuck, a work holdin face comprising radially arrangedrows 0 magnetized sections, the sections toward the center of said facebeing narrower, measured radially, than those removed from the center.

9. In a magnetic chuck, a work holding face comprising radiall arrangedrows of magnetized sections, wit nonmagnetic gaps between adjacentsections of adjacent rows said gaps being narrower at the center of saidface than at the edge thereof.

10. In a magnetic chuck, a plurality of magnetized pole piecesalternating in polarity, said pole pieces having isolated upwardprojections thereon Whose flush surfaces are separated by gaps ofnonmagnetic material, to form the Work holding face of the chuck.

11, In a magnetic chuck, a plurality of magnetized elements alternatingin polarity each of said elements roviding a row of spaced upstandingpro ections disposed in alternating relation to similar projections onadjacent elements, the flush surfaces of all 15 of said projectionsconstituting the Work holding face of the chuck.

Dated this 27th day of February, 1919.

OAKLEY S. WALKER. Witnesses:

NELLIE NEALEN, PaNnLorn COMBERBACH.

